In the past, there has been known, in connection with a saddle type vehicle such as a motorcycle, a construction in which a rear wheel as a driving wheel is rotatably supported at the rear end of a swing arm supported so as to be vertically swingable with respect to a vehicle body frame.
Patent Document 1 discloses a so-called cantilever-like swing arm in which only one arm portion supports the axle of the rear wheel, in which a driven sprocket, a rear wheel hub, etc. are fastened and fixed to a predetermined position by using a large-diameter nut screwed with a female screw provided on the outer periphery of both end portions of the axle.